Shock absorbers are designed to have certain damping characteristics which often can be a compromise from optimal damping characteristics for given driving or riding conditions. For example, characteristics suitable for driving on smooth roads where low frequency chassis movements are common may not be suitable for rough roads where high frequency wheel movements are common. The compromise results from the fact that the damping in conventional shock absorbers is produced from flow paths in the piston that are fixed. As these flow paths do not change regardless of the frequency of motion of the parts in the piston the damping properties are substantially consistent over all driving conditions.